Extensively so, though as TryTwice hinted the focus here has been more on HBAs than DAS. See the PCIe adapter, ASM1166, and similar threads. In general there’s not a lot of enthusiasm for SATA port multipliers due to a history of reliability issues and their intrinsic bandwidth constraints. For example, the JMB575 is a 1:5 multiplier so the five downstream ports share the upstream SATA link’s bandwidth. Since the JMS580 is USB 3 gen 1 (5 Gb/s) that’s not much of a constraint in this specific case but five SSDs can saturate gen 2x2.
Given all the complaints about them, I suspect many USB 3 gen 1 DASes are implemented with similar approaches. For gen 2 the ASM1352R’s a two port bridge (e.g. Mercury Elite Pro Dual) and the ASM235CM seems to be four (e.g. Mercury Elite Pro Quad). The AS5004U might also be ASM235CM.
I’ve googled some for ASM2362+ASM1166 type implementations and, while there’s likely something available, haven’t had luck finding higher bay count descriptions which indicate the chips used amidst all the single NVMe listings. Same with the ASM2364.